Subject testing on this study was completed. Preliminary analysis of the data showed that administration of cocaine by rapid intravenous injection (10 seconds) or by smoke inhalation ("crack") produces a highly concentrated wave or bolus of drug in the arterial circulation which is at least 10 times greater than occurs in venous circulation. Other means of cocaine abuse would not be expected to produce such high arterial drug levels. This bolus peaks within 30 seconds, and rapidly dissipates within a few minutes, corresponding to the peak impact of drug on cardiovascular and subjective parameters. These data show that the left side of the heart and the brain are exposed to concentrations of cocaine for a few minutes that are far in excess these of what was previously assumed to occur. Ongoing data analyses will help determine if the kinetics of the two routes differ either qualitatively or quantitatively, however, these preliminary analyses indicate that the inhalation of free base cocaine vapor or has the same, if not greater, physiologic potential to harm and addict as rapid intravenous injections.